A general punch tool will be briefly described below.
Specifically, the punch tool is held by a punch tool holding member in a punch press, and includes a cylindrical punch guide. Moreover, the punch guide has, on its lower side, a stripper part which presses a periphery of a part to be processed in a sheet-like work. In the stripper part, an insertion hole is formed.
In the punch guide, a punch body is movably provided in the vertical directions. The punch body has, on its lower side, a blade part which can be inserted into the insertion hole. Note that the blade part of the punch body can enter into a die hole in a die tool held by a die tool holding member in the punch press. Moreover, a punch head is provided at an upper end of the punch body, and a stripper spring which can bias the punch body is provided on a lower side of the punch head.
Furthermore, the punch tool includes one rotation control means for controlling rotation of the punch body with respect to the punch guide. The rotation control means includes: a key groove formed so as to vertically extend in the punch guide; and a key which is provided in the punch body and is movably fitted to the key groove in the vertical directions.
Accordingly, the work is moved in a horizontal direction to be set at a position for processing by the punch press. Thereafter, a ram in the punch press is moved downward, and the punch head is pressed from above. Accordingly, the entire punch tool is moved downward, and a periphery of a part to be processed in the work is pressed by the stripper part of the punch guide. Furthermore, by moving the ram downward, the punch body is moved downward relative to the punch guide against a biasing force of the stripper spring. Accordingly, the blade part of the punch body is inserted into the insertion hole. Thus, the punch tool and the die tool are allowed to collaborate to subject the part to be processed in the work to punching. Consequently, processed holes can be formed in the work. Note that, after having been moved downward, the ram is moved upward to return to its initial position.
Moreover, in the case where the work is subjected to nibbling, first, as described above, the processed holes are formed in the work. Thereafter, while slightly moving the work in the horizontal direction, the ram is repeatedly moved up and down. Thus, by allowing the punch tool and the die tool to continuously collaborate many times, slits, notches or the like having a predetermined shape can be formed in the work.
Note that, as a prior art relevant to the present invention, there is Japanese Patent Application Laid-open Publication No. Hei 8 (1996)-281348 (Patent Document 1).
Meanwhile, in order to fit the key to the key groove, it is required to set a width of the key groove to be slightly larger than a width of the key. For a minute clearance between the key groove and the key, the punch body is allowed to be displaced in a circumferential direction. Moreover, the circumferential displacement of the punch body can be suppressed to be smaller by improving fitting accuracy between the key and the key groove to reduce the minute clearance between the key and the key groove. However, improvement in the fitting accuracy between the key and the key groove increases costs of processing the punch tool and complicates fitting in assembly of the punch tool. Thus, it is not desirable to improve the fitting accuracy between the key and the key groove more than necessary. Therefore, in the case where the work is subjected to nibbling by allowing the punch tool and the die tool to continuously collaborate many times, rattling is caused between the punch body and the punch guide. Thus, there is a problem that accuracy of processing the work is deteriorated due to steps or the like caused in a punched surface (cut surface) of the work.
Meanwhile, a punch tool used while being attached to a punch press such as a turret punch press, for example, generally has a configuration as shown in FIG. 1. Specifically, in a punch tool 101, a punch driver 109 is movably fitted in the vertical directions to a cylindrical punch guide 107 movably supported in the vertical directions through a lifter spring 105 on a punch holder 103 such as an upper turret in a punch press. Between a punch head 111 provided on an upper end of the punch driver 109 and the punch guide 107, a stripper spring 113 is provided. Moreover, a punch body 115 including a punch blade part 115B on its lower end is detachably attached to a lower side of the punch driver 109 by means of an attachment bolt 117 and a key 119.
In the above configuration, even if the punch blade part 115B varies in shape, the punch guide 107, the punch driver 109 and the like can be commonly used by replacing the punch body 115. However, since the punch body 115 is relatively large, in the case where the entire punch body 115 is manufactured by using high-speed steel, cemented carbide or the like, there is a problem that much waste is incurred.
Therefore, there has been also proposed a configuration in which the punch body 115 is divided into a part of a punch chip including the punch blade part and a main body part of the punch body, and the punch chip is detachably attached to the main body part of the punch body.
Note that, as the foregoing relevant prior art, there is Japanese Patent Application Laid-open Publication No. 2002-45932 (Patent Document 2).
The following is a configuration of attaching a punch chip to a punch body according to the invention described in Patent Document 2.
Specifically, as shown in FIG. 2, instead of the punch body 115, a punch body 121 that can be attached to/detached from the punch driver 109 and a punch chip 123 including a punch blade part 123B are combined. In an upper surface of the punch body 121, a screw hole 125, into which the attachment bolt 117 can be screwed, and also a key groove 127, to/from which the key 119 is fitted/removed, are formed. Therefore, the punch body 121, instead of the conventional punch body 115, can be attached to the punch driver 109.
In a lower surface of the punch body 121, a screw hole 131 is formed, into which an attachment bolt 129 as an example of attachment tools can be screwed, the attachment bolt penetrating the punch chip 123 from below. Moreover, in the lower surface of the punch body, a plurality of pin holes 135 are provided, in which positioning pins 133 as an example of the attachment tools are attached. The punch chip 123 attached to the lower surface of the punch body 121 has a configuration including pin holes 137 as attachment holes, into/from which the positioning pins 133 are fitted/removed, and a through hole 139 through which the attachment bolt 129 can penetrate. The through hole 139 is provided in the center of the punch chip 123, and the pin holes 137 are provided at symmetrical positions on both sides of the through hole 139.
Therefore, when the punch chip 123 is attached to the punch body 121, even if the punch chip 123 is rotated in an arbitrary direction around an axis center of the through hole 139, the punch chip 123 can be attached to the punch body 121. Thus, the attachment can be facilitated.
However, in the case where, despite that dimensions of the punch chip 123 from its left end face to its right end face are within an allowable range, for example, a manufacturing error in manufacturing of the punch chip 123 causes a slight difference between a dimension from the axis center of the through hole 139 to the left end face and a dimension from the axis center thereof to the right end face, it is necessary to find out whether the through hole 139 is closer to the right end or closer to the left end from the center of the punch chip 123. Specifically, a fine adjustment of a clearance between a die hole provided in a die and the punch chip 123 is sometimes made so as not to set the clearance closer to one side.
Therefore, even if a dimensional deviation to one side or the like due to the manufacturing error in manufacturing of the punch chip 123 has been found out in manufacturing, the dimensional deviation to one side becomes unfindable when the punch chip 123 is attached to the punch body 121. Thus, there is a problem that it is necessary to make measurements again.
The present invention was made to solve the problems as described above. It is a first object of the present invention to provide a punch tool which enables improvement in accuracy of processing a work by suppressing rattling between a punch body and a punch guide when nibbling is performed and by eliminating almost all steps or the like in a punched surface (cut surface) of the work.
It is a second object of the present invention to provide a punch tool which makes it possible to easily find out the deviation to one side as a dimensional error even after a punch chip is attached to a punch body.